1. Field of the Invention
This invention relates to spray nozzles suitable for use in creating spray patterns according to prescribed conditions and especially for handling strong solutions such as found in industry and including insecticides which normally result in erosion of metal nozzles such as those made of brass, or the like.
2. Description of the Prior Art
Heretofore, metal nozzles have been utilized with metering orifices which have been used in the upstream side of the spray nozzles to reduce the pressure and the flow to the nozzle. A common form of such restrictions consisted of a flat washer, or disc, having a round hole in the center, which was of a size to provide the desired restriction in accordance with the requirements of specified conditions to be met by the nozzle. The round center hole permitted maximum flow through the restriction consistent with the size of the hole and the flow issued through the restriction as a high velocity stream such that the desired spray performance of the associated nozzle was disturbed.
Ordinarily, when such a conventional orifice plate is used in a spray system, the flow through the orifice issues as a high velocity stream and this velocity is relative to the differential pressure across the orifice. When this high velocity stream impinges on the orifice of the nozzle because of the location of the orifice plate relative to the nozzle, this high velocity stream does not allow the orifice to flood, or fill and striking the nozzle orifice, disturbs the spray performance of the nozzle and frequently it is necessary to provide additional piping in ordr to maintain a minimum distance between the nozzle and orifice plate. Nozzles of this type usually have been made of metal such as brass, or the like.
An example of this condition is found in the industry relating to irrigation of farm fields, where a system of spray nozzles on a distributor pipe rotates about a central pivot. The nozzle nearest to this central pivot point is closest to the supply pump and requires the least flow and the lowest pressure. Efforts to compensate for this condition involved the use of nozzles having small orifice diameters as a means to control the flow through the nozzle closest to the pivot point but the spray issuing from these nozzles are finely atomized due to the higher pressure and consequently was adversely affected by wind conditions and also tended to cause the nozzle to clog. Under these conditions, a nozzle having a larger capacity was necessary and this was used in conjunction with a conventional metering orifice upstream of the nozzle to control the flow and reduce the pressure on the nozzle and produce a spray containing larger droplets. These conventional orifice plates were made of a size proportioned in accordance with the nozzle used and the spray desired and it was necessary to maintain a minimum spacing between the orifice plate and the nozzle orifice in an effort to avoid disturbance of the spray pattern discharged from the orifice.